Position-measuring devices of this kind are used, in particular, in machine tools for measuring the position of a tool relative to a workpiece to be machined, in coordinate measuring machines for determining the position and dimensions of test objects, as well as in the semiconductor industry. In this context, the scale is directly mounted on a first object, for example, the drive unit (for example, linear motor), or the scale is mounted on a component driven by the drive unit. Opposite the moving scale, the scanning unit of the position-measuring device is affixed to a second object, whose position is to be measured, in a stationary manner.
The temperature-induced displacement of the scale relative to the first object is to be taken into account during the position measurement. To this end, the International Patent Application WO 2012/114168 A1 discusses using a probe at the reference point of the scale to directly measure the displacement of the scale. Temperature sensors are assigned to the scale in order to record the temperature-induced displacement of the scale outside of the reference point. At these positions outside of the reference point, the temperature-induced displacement of the scale can be ascertained from the measured temperature and the thermal expansion coefficient of the scale material.